Incandescent lamp



' (iIo'ModaL) J. T. LISTER. INGANDESGENT LAMP.

Patented Sept. 22, 1896.

Judah UNITED STATES PATENT OFFICE.

JOHN T. LISTER, OF CLEVELAND, OHIO.

INCANDESCENT LAMP.

SPECIFICATION forming part of Letters Patent No. 568,262, dated September 22, 1896. Application filed April 25, 1896. Serial No. 589,143. (No model.)

To all whom it may concern: 7

Be it known that I, JOHN T. LISTER, a citizen of the United States, and a resident of Cleveland, county of Ouyahoga, State of Ohio, have invented certain new and useful Improvements in Incandescent Lamps, of which I hereby declare the following to be a full, clear, and exact description, such as will enable others skilled in the art to which it appertains to make and use the same.

My invention relates to improvements in incandescentlamps, and the objects of theinvention are to provide means for increasing the durability and power of the lamp. My invention further provides a form of lamp which affords a free passage to the light in all directions and presents no interfering parts to cast shadows.

My invention consists in the shell of symmetrical form and in the adoption of a pair of filaments and circuit-terminals therefor, the circuit-terminals for one pair of filaments being at one end of the shell and the circuitterminals for the other filament being at the other end of the shell. These circuit-terminals are so placed in the shell as to readily make exterior connections and the filaments are so mounted in the shell as to pass one another without touching at the extremities.

My invention further consists in the construction and arrangement of the various details, as hereinafter described, shown in the accompanying drawings, and more specifically pointed out in the claim.

In the accompanying drawings, Figure 1 is a side elevation of the shell and inclosed filaments. Fig. 2 is a plan View of the device. Fig. 3 is a detail of the cap.

In the figures, 1 is the shell.

2 are the filaments, inserted in the closed extremities at 3 and 4 in such a manner as not to touch one another. The cap 8 fits closely over the shell extremities and small projections 10 spring into the recesses 11 in the shell to maintain the parts securely in contact. A slot 12 permits the cap to expand sufficiently for this purpose. The contactpoints for the extremities of the lamp-circuit are shown at 6 and 7 in the cap 8, the extremity 6 being insulated at 9 from the cap.

I do not claim the exact shape of the shell, although the shape of the extremities should be uniform, nor do I claim the exact method of hanging the lamp, Whether horizontally or Vertically. In neither position could shadows interfere with the light.

It will be seen that by means of suitable connections with the circuit-wires one or both lamps can be utilized, or one lamp can be used continuously until worn out, when the other can be lighted, thus doubling the life or power of the lamp at pleasure.

Having described my invention, what I claim as new, and desire to secure by Letters Patent, is

In an incandescent lamp, the combination with a shell, of a pair of filaments and circuit-terminals therefor, the circuit-terminals for one filament being at one end of the shell and the circuit-terminals for the other filament being atthe other end of the shell substantially as set forth.

JOHN T. LISTER.

W'itnesses:

WM. M. MONROE, GEO. O. WILLET. 

